x86: fix reboot on apu2 boards

PC Engines apu2 needs to use the PCI reboot method, otherwise it can
hang.

Signed-off-by: Felix Fietkau <nbd@nbd.name>

target/linux/x86/patches-4.9/200-pcengines-apu2-reboot.patch

@@ -0,0 +1,19 @@
+--- a/arch/x86/kernel/reboot.c
++++ b/arch/x86/kernel/reboot.c
+@@ -443,6 +443,16 @@ static struct dmi_system_id __initdata r
+ 		},
+ 	},
+ 
++	/* PC Engines */
++	{	/* Handle problems with rebooting on PC Engines apu2 */
++		.callback = set_pci_reboot,
++		.ident = "PC Engines apu2",
++		.matches = {
++			DMI_MATCH(DMI_BOARD_VENDOR, "PC Engines"),
++			DMI_MATCH(DMI_BOARD_NAME, "apu2"),
++		},
++	},
++
+ 	/* Sony */
+ 	{	/* Handle problems with rebooting on Sony VGN-Z540N */
+ 		.callback = set_bios_reboot,